JPS5824628B2 - engine ignition system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact ignition device for an engine that arbitrarily controls the ignition timing of the engine.

Conventionally, in this type of engine ignition system, an ignition voltage is generated on the secondary side by controlling the primary current of the ignition coil by operating a switching element such as a thyristor or transistor using an ignition signal generated at the engine ignition timing. There is.

However, in this case, the ignition signal voltage generated in the signal generator coil in synchronization with the rotation of the engine is directly supplied to the switching element as the ignition signal, so the ignition timing advance characteristic is determined by the output waveform of the ignition signal. However, it had the disadvantage that it could not meet the advance angle characteristics originally required for internal combustion engines.

SUMMARY OF THE INVENTION In view of the above drawbacks, the present invention provides an engine ignition system that arbitrarily controls the advance start timing of engine ignition timing to satisfy the advance characteristics required by the engine.

The embodiment shown in FIG. 1 will be described below.

In Fig. 1, reference numeral 1 denotes a power generating coil that is built into an AC magnet generator driven by an engine (not shown) and generates an AC output voltage in synchronization with the rotation of the engine, and 2 rectifies the AC output of this power generating coil 1. A diode, 3 is a capacitor charged by this rectified output, 4 is an ignition coil, 5 is a spark plug connected to the ignition coil 40 secondary coil, 6 is a thyristor which is a switching element, and the electric charge charged in capacitor 3 is transferred to the above. The ignition coil 40 constitutes a discharge circuit to discharge to the primary coil.

Reference numeral 1 denotes a signal shaping circuit that constitutes a main part of the present invention.

That is, 8 is a signal generator driven by the engine, which generates an AC output voltage whose value increases or decreases as the engine speed increases or decreases.

9 is a diode that passes the output of the AC output of the signal generator 8 having the polarity (direction a shown in FIG. 1) that provides an ignition signal to the gate of the thyristor 6; the output of the signal generator 8 passes through the diode 9; is supplied to the gate of the thyristor 6 through a parallel circuit of a capacitor 10 and a resistor 11.

12 is the other half wave (first
A diode is connected between the gate and cathode of the thyristor 6 in order to pass the signal (direction b shown in the figure), while a resistor 14 and a zener diode 13 are connected in parallel with the diode 9.
series circuit is connected.

This series circuit corresponds to the circuit means in the claims.

Next, the operation of the apparatus configured as described above will be explained with reference to the operational waveform diagram in FIG. 2a and the characteristic curve diagram in FIG. 3.

First, the alternating current output generated in the generator coil 1 of the magnet generator by the rotation of the engine is rectified by the diode 2 and charges the capacitor 3.

Therefore, when the ignition timing of the engine comes, the ignition signal voltage (V in FIG. 2a) generated in the signal generator 8.

) is rectified by diode 9, capacitor 10, resistor 11
Power is supplied to the gate of the thyristor 6 through the parallel circuit.

The thyristor 6 receives this signal and becomes conductive, so the charge in the capacitor 3 is discharged to the primary coil of the ignition coil 4 through the thyristor 6, and an ignition voltage is generated in the secondary coil. Plug 5 produces a spark discharge.

Figure 2 A shows the AC output V of the signal generator 8.

In the figure, n15 n2,
n3 (n.

<n2<n3) indicates the rotational speed of the engine, and the positive and negative half waves of this AC output waveform correspond to the polarities in the a direction and b direction shown in FIG. 1, respectively.

The positive half wave (direction a in FIG. 1) of the AC output of the signal generator 8 is rectified by the diode 9 and charges the capacitor 10 to the polarity shown in FIG.
1 based on the discharge time constant determined by the capacitor 10 and the resistor 11 (Vc waveform at the beginning of Figure 2).

Now, as the engine speed increases, the AC output of the signal generator 8 increases, but since the discharge time constant of the capacitor 10 is constant, if the AC output increases, the output of the signal generator 8 will increase when the next ignition signal is generated. The voltage Vc of 10 also increases.

Thus, the ignition signal Vg supplied to the gate of the thyristor 6
As shown in Figure 2 C, the engine speed is from nl to n2.
, the ignition timing of the engine is kept constant at time t4, that is, the ignition timing of the engine is kept constant.

Next, the engine speed further increases as shown in FIG.
When the combined voltage value with the output voltage (in the direction shown in the figure) becomes equal to or higher than the zener voltage Vz of the zener diode 13, the diode 12, Since the charge in the capacitor 10 is discharged via the zener diode 13 and the resistor 14, the charge voltage value of the capacitor 10 decreases at the time when the next ignition signal is generated. The ignition signal Vg to be supplied with power is generated at time t3, and the ignition timing of the engine is advanced.

As described above, the ignition timing remains almost constant as the engine speed increases until the zener diode 13 becomes conductive (the
(Fig. After conduction, the ignition timing is gradually advanced (Y in Figure 3) as the rotation speed increases, and finally becomes constant (
Figure 3 Z).

Figure 3 compares the ignition timing advance characteristic θ with respect to engine speed n between the device of the present invention and the conventional device. It shows.

As described above, by providing the signal shaping circuit 7, the advance characteristics of the ignition timing can be changed in various ways.

That is, by changing the capacitance of the capacitor 10, the values of the resistors 11 and 140, the voltage characteristics of the signal generator 9, and the Zener voltage of the Zener diode 13, the advance angle characteristics required by the engine can be obtained.

Various modifications of the signal shaping circuit 70 will be described with reference to FIGS. 4 to 1.

FIG. 4 shows the first other embodiment, in which the Zener diode 13 is connected to one having switching characteristics, for example, a SIDAC 15.

FIG. 5 shows a second other embodiment, in which the capacitor 1
A resistor 16 is connected in series to the charging circuit of 0 to limit the charging current of the capacitor 10 and prevent delay in ignition timing at high speed rotation.

FIG. 6 shows a third other embodiment, in which the diode 9
is changed to a Zener diode 13.

FIG. 7 shows a fourth other embodiment, in which the diode 9
to Zener diode 13, and diode 12 to resistor 1
4 and can be used if the gate reverse breakdown voltage of the thyristor 6 can be guaranteed.

Although the above description is applied to a capacitor charge/discharge type ignition device, it is also possible to apply it to other ignition devices operated by a control signal, such as a current cut-off type ignition device using a transistor or the like.

As described above, according to the present invention, it is possible to obtain a linear advance characteristic as the engine ignition timing by simply adding a simple circuit. A remarkable effect in practical use can be obtained by being able to correspond to various required advance angle characteristics.

[Brief Description of the Drawings] Fig. 1 is an electric circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram for explaining the operation of the device shown in Fig. 1, and Fig. 3 is a waveform diagram of the device shown in Fig. 1. Characteristic curve diagram for explaining the operation, Fig. 4,
FIG. 5, FIG. 6, and FIG. 7 are electrical circuit diagrams showing other embodiments of the present invention. In the figure, 1 is a generator coil, 2, 9, 12 are diodes, 3
, 10 is a capacitor, 4 is an ignition coil, 5 is a spark plug, 6 is a cyrisk, 7 is a signal shaping circuit, 8 is a signal generator, 13 is a zener diode, ICl3, 16 is a resistor, 1
5 is a side dunk.

Claims (1)

[Scope of Claims] 1. A signal generator that generates alternating current output in both positive and negative directions that is synchronized with the rotation of the engine and whose value increases or decreases as the rotation speed increases or decreases;
A switching element that controls the energizing current of the ignition coil to generate an ignition voltage, a parallel circuit consisting of a resistor and a capacitor connected to a power supply path of the unidirectional output of the AC output to the control input terminal of the switching element, and An engine ignition system comprising circuit means for discharging the charge charged in the capacitor and changing the operating timing of the switching element when the composite voltage value of the other output voltage of the AC output and the charging voltage of the capacitor reaches a predetermined value. Device. 2. The engine ignition system according to claim 1, wherein the circuit means comprises a resistor and a Zener diode.